Construction on the Summerhouse was begun in 1879 and completed in late 1880 or early 1881 by landscape architect Frederick Law Olmsted. Olmsted had been appointed by Congress in 1874 to develop and improve the Capitol grounds, which had been enlarged in response to the addition of the north and south wings of the Capitol. He included the Summerhouse in response to complaints that visitors to the Capitol could find no water nor any place to rest on their journey. In addition, he designed it as a setting for decorative vegetation.
Olmsted devoted much thought to the Summerhouse. He was concerned that the structure not intrude upon the landscape, but he was also careful to ensure that it was sufficiently public to prevent its use for improper purposes. Several of his letters show his active interest in the progress of the building and its landscaping.
The letters also indicate areas in which the completed structure differed from his plans. For example, he intended that the overflow from the fountain should operate a small device called the "carillon" to produce soft musical chimes; however, the device could not be made to work properly and so was never installed. Olmsted originally planned two Summer Houses for the Capitol Grounds (references in two of his letters identify a northern and a southern Summer House); however, congressional objections to the northern Summer House before its completion prevented the construction of the southern one.